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[texts]Orthodox Gravity - A. Y. Shiekh
A scalar field theory is investigated within the context of orthodox quantum gravity.
Downloads: 678
[texts]Gravity Balls - Daksh Lohia
The existence of non trivial, non topological solutions in a class of induced, effective gravity models arising out of a non minimally coupled scalar field is established. We shall call such solutions ``Gravity Balls'' as the effective gravitational constant inside the soliton differs from its effective value outside.
Downloads: 633
[texts]Stability structures, motivic Donaldson-Thomas invariants and cluster transformations - Maxim Kontsevich
We define new invariants of 3d Calabi-Yau categories endowed with a stability structure. Intuitively, they count the number of semistable objects with fixed class in the K-theory of the category ("number of BPS states with given charge" in physics language). Formally, our motivic DT-invariants are elements of quantum tori over a version of the Grothendieck ring of varieties over the ground field. Via the quasi-classical limit "as the motive of affine line approaches to 1" we obtain numerical DT-...
Downloads: 627
[texts]W-Gravity - C. M. Hull
The geometric structure of theories with gauge fields of spins two and higher should involve a higher spin generalisation of Riemannian geometry. Such geometries are discussed and the case of $W_\infty$-gravity is analysed in detail. While the gauge group for gravity in $d$ dimensions is the diffeomorphism group of the space-time, the gauge group for a certain $W$-gravity theory (which is $W_\infty$-gravity in the case $d=2$) is the group of symplectic diffeomorphisms of the cotangent bundle of ...
Downloads: 624
[texts]Nonquantum Gravity - Stephen Boughn
One of the great challenges for 21st century physics is to quantize gravity and generate a theory that will unify gravity with the other three fundamental forces of nature. This paper takes the (heretical) point of view that gravity may be an inherently classical, i.e., nonquantum, phenomenon and investigates the experimental consequences of such a model. At present there is no experimental evidence of the quantum nature of gravity and the liklihood of definitive tests in the future is not at al...
Downloads: 566
[texts]Spinor Gravity - A. Hebecker
A unified description of all interactions could be based on a higher-dimensional theory involving only spinor fields. The metric arises as a composite object and the gravitational field equations contain torsion-corrections as compared to Einstein gravity. Lorentz symmetry in spinor space is only global, implying new goldstone-boson-like gravitational particles beyond the graviton. However, the Schwarzschild and Friedman solutions are unaffected at one loop order...
Downloads: 467
[texts]The benefits of the orthogonal LSM models - Z. Mikulasek
In the last few decades both the volume of high-quality observing data on variable stars and common access to them have boomed; however the standard used methods of data processing and interpretation have lagged behind this progress. The most popular method of data treatment remains for many decades Linear Regression (LR) based on the principles of Least Squares Method (LSM) or linearized LSM. Unfortunately, we have to state that the method of linear regression is not as a rule used accordingly ...
Downloads: 465
[texts]Liouville gravity from Einstein gravity - D. Grumiller
We show that Liouville gravity arises as the limit of pure Einstein gravity in 2+epsilon dimensions as epsilon goes to zero, provided Newton's constant scales with epsilon. Our procedure - spherical reduction, dualization, limit, dualizing back - passes several consistency tests: geometric properties, interactions with matter and the Bekenstein-Hawking entropy are as expected from Einstein gravity.
Downloads: 458
[texts]About Time - M. D. Maia
The concept of time is discussed in the context of the canonical formulation of the gravitational field. Using a hypersurface orthogonal foliation, the arbitrariness of the lapse function is eliminated and the shift vector vanishes, allowing a consistent definition of time.
Downloads: 433
[texts]Big Bang Nucleosynthesis - Keith A. Olive
The concordance of standard big bang nucleosynthesis theory and the related observations of the light element isotopes (including some new higher \he4 abundances) will be reviewed. Implications of BBN on chemical evolution, dark matter and constraints on particle properties will be discussed.
Downloads: 408
[texts]The Distributed Network Processor: a novel off-chip and on-chip interconnection network architecture - Andrea Biagioni
One of the most demanding challenges for the designers of parallel computing architectures is to deliver an efficient network infrastructure providing low latency, high bandwidth communications while preserving scalability. Besides off-chip communications between processors, recent multi-tile (i.e. multi-core) architectures face the challenge for an efficient on-chip interconnection network between processor's tiles...
Downloads: 378
[texts]Twisted planes - Jorge A. Guccione
Let k be a commutative ring. We find and characterize a new family of twisted planes (i. e. associative unitary k-algebra structures on the k-module k[X,Y], having k[X] and and k[Y] as subalgebras).Similar results are obtained for the k-module of two variables power series k[[X,Y]].
Downloads: 357
[texts]Testing Big Bang Nucleosynthesis - Gary Steigman
Big Bang Nucleosynthesis (BBN), along with the cosmic background radiation and the Hubble expansion, is one of the pillars ofthe standard, hot, big bang cosmology since the primordial synthesis of the light nuclides (D, $^3$He, $^4$He, $^7$Li) must have occurred during the early evolution of a universe described by this model. The overall consistency between the predicted and observed abundances of the light nuclides, each of which spans a range of some nine orders of magnitude, provides impress...
Downloads: 347
[texts]Computational Complexity Analysis of Simple Genetic Programming On Two Problems Modeling Isolated Program Semantics - Greg Durrett
Analyzing the computational complexity of evolutionary algorithms for binary search spaces has significantly increased their theoretical understanding. With this paper, we start the computational complexity analysis of genetic programming. We set up several simplified genetic programming algorithms and analyze them on two separable model problems, ORDER and MAJORITY, each of which captures an important facet of typical genetic programming problems...
Downloads: 343
[texts]Discrete analogue computing with rotor-routers - James Propp
Rotor-routing is a procedure for routing tokens through a network that can implement certain kinds of computation. These computations are inherently asynchronous (the order in which tokens are routed makes no difference) and distributed (information is spread throughout the system). It is also possible to efficiently check that a computation has been carried out correctly in less time than the computation itself required, provided one has a certificate that can itself be computed by the rotor-ro...
Downloads: 325
[texts]Mean field frozen percolation - Balazs Rath
We define a modification of the Erdos-Renyi random graph process which can be regarded as the mean field frozen percolation process. We describe the behavior of the process using differential equations and investigate their solutions in order to show the self-organized critical and extremum properties of the critical frozen percolation model. We prove two limit theorems about the distribution of the size of the component of a typical frozen vertex.
Downloads: 298
[texts]A Matrix Big Bang - Ben Craps
The light-like linear dilaton background represents a particularly simple time-dependent 1/2 BPS solution of critical type IIA superstring theory in ten dimensions. Its lift to M-theory, as well as its Einstein frame metric, are singular in the sense that the geometry is geodesically incomplete and the Riemann tensor diverges along a light-like subspace of codimension one. We study this background as a model for a big bang type singularity in string theory/M-theory...
Downloads: 288
[texts]Robust Estimation of Operational Risk - Nataliya Horbenko
According to the Loss Distribution Approach, the operational risk of a bank is determined as 99.9% quantile of the respective loss distribution, covering unexpected severe events. The 99.9% quantile can be considered a tail event. As supported by the Pickands-Balkema-de Haan Theorem, tail events exceeding some high threshold are usually modeled by a Generalized Pareto Distribution (GPD). Estimation of GPD tail quantiles is not a trivial task, in particular if one takes into account the heavy tai...
Downloads: 250
[texts]Pre-big bang in M-theory - Marco Cavaglia
We discuss a simple cosmological model derived from M-theory. Three assumptions lead naturally to a pre-big bang scenario: (a) 11-dimensional supergravity describes the low-energy world; (b) non-gravitational fields live on a three-dimensional brane; and (c) asymptotically past triviality.
Downloads: 238
[texts]A proposal that explains the Pioneer anomaly - Antonio F. Ranada
We propose here an explanation of the Pioneer anomaly which is not in conflict with the cartography of the solar system. In our model, the spaceship does not suffer any extra acceleration but follows the trajectory predicted by standard gravitational theory. The observed acceleration is not real but apparent and has the same observational footprint as a deceleration of astronomical time with respect to atomic time...
Downloads: 226
[texts]Hedging strategies with a put option and their failure rates - Guanghui Huang
The problem of stock hedging is reconsidered in this paper, where a put option is chosen from a set of available put options to hedge the market risk of a stock. A formula is proposed to determine the probability that the potential loss exceeds a predetermined level of Value-at-Risk, which is used to find the optimal strike price and optimal hedge ratio. The assumptions that the chosen put option finishes in-the-money and the constraint of hedging budget is binding are relaxed in this paper...
Downloads: 223
[texts]Einstein, Kant, and Taoism - Y. S. Kim
It is said that Einstein's conceptual base for the theory of relativity was the philosophy formulated by Immanuel Kant. Then, is it possible to see how Kant played a role in Einstein's thinking without reading Kant's books? This question arises because it is not possible for physicists to read Kant's writings. Yes, it is possible if we use the method of physics. It is known also that Kant's mode of thinking was profoundly affected by the geography of Koenigsberg where he spent eighty years of en...
Downloads: 220
[texts]Big Bang Models in String Theory - Ben Craps
These proceedings are based on lectures delivered at the "RTN Winter School on Strings, Supergravity and Gauge Theories", CERN, January 16 - January 20, 2006. The school was mainly aimed at Ph.D. students and young postdocs. The lectures start with a brief introduction to spacetime singularities and the string theory resolution of certain static singularities. Then they discuss attempts to resolve cosmological singularities in string theory, mainly focusing on two specific examples: the Milne or...
Downloads: 218
[texts]Quantum Gravity - Enrique Alvarez
General lectures on quantum gravity.
Downloads: 218
[texts]Information Measures of Complexity, Emergence, Self-organization, Homeostasis, and Autopoiesis - Nelson Fernandez
This chapter reviews measures of emergence, self-organization, complexity, homeostasis, and autopoiesis based on information theory. These measures are derived from proposed axioms and tested in two case studies: random Boolean networks and an Arctic lake ecosystem. Emergence is defined as the information produced by a system or process. Self-organization is defined as the opposite of emergence, while complexity is defined as the balance between emergence and self-organization...
Downloads: 213
[texts]Event management for large scale event-driven digital hardware spiking neural networks - Louis-Charles Caron
The interest in brain-like computation has led to the design of a plethora of innovative neuromorphic systems. Individually, spiking neural networks (SNNs), event-driven simulation and digital hardware neuromorphic systems get a lot of attention. Despite the popularity of event-driven SNNs in software, very few digital hardware architectures are found. This is because existing hardware solutions for event management scale badly with the number of events...
Downloads: 204
[texts]MATLAB codes for teaching quantum physics: Part 1 - Rafael Garcia
Among the ideas to be conveyed to students in an introductory quantum course, we have the pivotal idea championed by Dirac that functions correspond to column vectors (kets) and that differential operators correspond to matrices (ket-bras) acting on those vectors. The MATLAB (matrix-laboratory) programming environment is especially useful in conveying these concepts to students because it is geared towards the type of matrix manipulations useful in solving introductory quantum physics problems...
Downloads: 204
[texts]Smooth projective planes - Benjamin McKay
Using symplectic topology and the Radon transform, we prove that smooth 4-dimensional projective planes are diffeomorphic to $\mathbb{CP}^2$. We define the notion of a plane curve in a smooth projective plane, show that plane curves in high dimensional regular planes are lines, prove that homeomorphisms preserving plane curves are smooth collineations, and prove a variety of results analogous to the theory of classical projective planes.
Downloads: 198
[texts]A defect mediated lamellar to isotropic transition of amphiphile bilayers - Antara Pal
We report the observation of a novel isotropic phase of amphiphile bilayers in a mixed system consisting of the ionic surfactant, sodium docecylsulphate (SDS), and the organic salt p-toludine hydrochloride (PTHC). This system forms a collapsed lamellar ($L_\alpha$) phase over a wide range of water content, which transforms into an isotropic phase on heating. This transition is not observed in samples without excess water, where the $L_\alpha$ phase is stable at higher temperatures...
Downloads: 198
[texts]Three-dimensional brittle fracture: configurational-force-driven crack propagation - Lukasz Kaczmarczyk
This paper presents a computational framework for quasi-static brittle fracture in three dimensional solids. The paper set outs the theoretical basis for determining the initiation and direction of propagating cracks based on the concept of configurational mechanics, consistent with Griffith's theory. Resolution of the propagating crack by the finite element mesh is achieved by restricting cracks to element faces and adapting the mesh to align it with the predicted crack direction...
Downloads: 196
[texts]Astrophysics in 2005 - V. Trimble
We bring you, as usual, the Sun and Moon and stars, plus some galaxies and a new section on astrobiology. Some highlights are short (the newly identified class of gamma-ray bursts, and the Deep Impact on Comet 9P/ Tempel 1), some long (the age of the universe, which will be found to have the Earth at its center), and a few metonymic, for instance the term "down-sizing" to describe the evolution of star formation rates with redshift.
Downloads: 196
[texts]Correspondences between projective planes - June Huh
We characterize integral homology classes of the product of two projective planes which are representable by a subvariety.
Downloads: 192
[texts]Conics in normed planes - Ákos G. Horváth
We study the generalized analogues of conics for normed planes by using the following natural approach: It is well known that there are different metrical definitions of conics in the Euclidean plane. We investigate how these definitions extend to normed planes, and we show that in this more general framework these different definitions yield, in almost all cases, different classes of curves.
Downloads: 184
[texts]Bethe Ansatz for Heisenberg XXX Model - Shao-shiung Lin
We investigate Bethe Ansatz equations for the one-dimensional spin-$\frac{1}{2}$ Heisenberg XXX chain with a special interest in a finite system. Solutions for the two-particle sector are obtained. The ground state in antiferromagnetic case has been analytically studied through the logarithmic form of Bethe Ansatz equations.
Downloads: 180
[texts]Software Design Document, Testing, Deployment and Configuration Management of the UUIS--a Team 2 COMP5541-W10 Project Approach - Omer Shahid Ahmad
The Software Design Document of UUIS describes the prototype design details of the system architecture, database layer, deployment and configuration details as well as test cases produced while working the design and implementation of the prototype. The requirements specification of UUIS are detailed in arXiv:1005.0783.
Downloads: 177
[texts]Ratliff-Rush Monomial Ideals - Veronica Crispin Quiñonez
Let $I$ be a regular $\mathfrak m$-primary ideal in $(R,\mathfrak m,k)$. Then the Ratliff-Rush ideal associated to $I$ is denoted by $\bar I$ and is defined as the largest ideal containing $I$ with the same Hilbert polynomial as $I$. In this paper we present a method to compute Ratliff-Rush ideals for a certain class of monomial ideals in the rings $k[x,y]$ and $k[[x,y]]$. We find an upper bound for the Ratliff-Rush reduction number for an ideal in this class...
Downloads: 177
[texts]Evolution of Swarm Robotics Systems with Novelty Search - Jorge Gomes
Novelty search is a recent artificial evolution technique that challenges traditional evolutionary approaches. In novelty search, solutions are rewarded based on their novelty, rather than their quality with respect to a predefined objective. The lack of a predefined objective precludes premature convergence caused by a deceptive fitness function. In this paper, we apply novelty search combined with NEAT to the evolution of neural controllers for homogeneous swarms of robots...
Downloads: 176
[texts]Results on fuzzy soft topological spaces - J. Mahanta
B. Tanay et. al. introduced and studied fuzzy soft topological spaces. Here we introduce fuzzy soft point and study the concept of neighborhood of a fuzzy soft point in a fuzzy soft topological space. We also study fuzzy soft closure and fuzzy soft interior. Separation axioms and connectedness are introduced and investigated for fuzzy soft topological spaces.
Downloads: 170
[texts]Pioneer Anomaly and the Kuiper Belt mass distribution - O. Bertolami
Pioneer 10 and 11 were the first probes sent to study the outer planets of the Solar System and Pioneer 10 was the first spacecraft to leave the Solar System. Besides their already epic journeys, Pioneer 10 and 11 spacecraft were subjected to an unaccounted effect interpreted as a constant acceleration toward the Sun, the so-called Pioneer anomaly. One of the possibilities put forward for explaining the Pioneer anomaly is the gravitational acceleration of the Kuiper Belt...
Downloads: 169
[texts]An Empirical Investigation of the Forward Interest Rate Term Structure - Andrew Matacz
In this paper we study empirically the Forward Rate Curve (FRC) of 5 different currencies. We confirm and extend the findings of our previous investigation of the U.S. Forward Rate Curve. In particular, the average FRC follows a square-root law, with a prefactor related to the spot volatility, suggesting a Value-at-Risk like pricing. We find a striking correlation between the instantaneous FRC and the past spot trend over a certain time horizon, in agreement with the idea of an extrapolated tren...
Downloads: 168
[texts]`Tail-end' Bondi-Hoyle accretion in young star clusters: Implications for disks, planets, and stars - Henry B. Throop
Young stars orbiting in the gravitational potential well of forming star clusters pass through the cluster's dense molecular gas and can experience Bondi-Hoyle accretion from reservoirs outside their individual protostellar cloud cores. Accretion can occur for several million years after the stars form, but before the cluster disperses. This accretion is predominantly onto the disk and not the star...
Downloads: 167
[texts]Curious numerical coincidence to the Pioneer anomaly - Liviu Ivanescu
One noticed a pure numerical coincidence between the Pioneer spacecrafts deceleration anomaly and (gamma-1), with gamma the Lorentz factor. The match is not only for distances larger than 20 AU, but even for the observed slop between 10 and 20 AU.
Downloads: 165
[texts]Primordial Big Bang Nucleosynthesis - Keith A. Olive
Big Bang Nucleosynthesis is the theory of the production of the the light element isotopes of D, He3, He4, and Li7. After a brief review of the essential elements of the standard Big Bang model at a temperature of about 1 MeV, the theoretical input and predictions of BBN are discussed. The theory is tested by the observational determinations of the light element abundances and the current status of these observations is reviewed...
Downloads: 164
[texts]What we don't know about time - Vijay Balasubramanian
String theory has transformed our understanding of geometry, topology and spacetime. Thus, for this special issue of Foundations of Physics commemorating "Forty Years of String Theory", it seems appropriate to step back and ask what we do not understand. As I will discuss, time remains the least understood concept in physical theory. While we have made significant progress in understanding space, our understanding of time has not progressed much beyond the level of a century ago when Einstein in...
Downloads: 163
[texts]The Mexican Hat Wavelet Family. Application to point source detection in CMB maps - J. Gonzalez-Nuevo
We propose a new detection technique in the plane based on an isotropic wavelet family. This family is naturally constructed as an extension of the Gaussian-Mexican Hat Wavelet pair and for that reason we call it the Mexican Hat Wavelet Family (MHWF). We show the performance of these wavelets when dealing with the detection of extragalactic point sources in cosmic microwave background (CMB) maps: a very important issue within the most general problem of the component separation of the microwave ...
Downloads: 162
[texts]Big Bang Nucleosynthesis - Keith A. Olive
A brief review of standard big bang nucleosynthesis theory and the related observations of the light element isotopes is presented. Implications of BBN on chemical evolution and constraints on particle properties will also be discussed.
Downloads: 160
[texts]From Big Crunch to Big Bang - Justin Khoury
We consider conditions under which a universe contracting towards a big crunch can make a transition to an expanding big bang universe. A promising example is 11-dimensional M-theory in which the eleventh dimension collapses, bounces, and re-expands. At the bounce, the model can reduce to a weakly coupled heterotic string theory and, we conjecture, it may be possible to follow the transition from contraction to expansion...
Downloads: 158
[texts]Data-rich astronomy: mining synoptic sky surveys - Stefano Cavuoti
In the last decade a new generation of telescopes and sensors has allowed the production of a very large amount of data and astronomy has become, a data-rich science; this transition is often labeled as: "data revolution" and "data tsunami". The first locution puts emphasis on the expectations of the astronomers while the second stresses, instead, the dramatic problem arising from this large amount of data: which is no longer computable with traditional approaches to data storage, data reduction...
Downloads: 155
[texts]Interest-Based vs. Social Person-Recommenders in Social Networking Platforms - Georg Groh
Social network based approaches to person recommendations are compared to interest based approaches with the help of an empirical study on a large German social networking platform. We assess and compare the performance of different basic variants of the two approaches by precision / recall based performance with respect to reproducing known friendship relations and by an empirical questionnaire based study...
Downloads: 154
[texts]Search for a Standard Explanation of the Pioneer Anomaly - John D. Anderson
The data from Pioneer 10 and 11 shows an anomalous, constant, Doppler frequency drift that can be interpreted as an acceleration directed towards the Sun of a_P = (8.74 \pm 1.33) x 10^{-8} cm/s^2. Although one can consider a new physical origin for the anomaly, one first must investigate the contributions of the prime candidates, which are systematics generated on board. Here we expand upon previous analyses of thermal systematics...
Downloads: 154
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